TOKYO, Oct. 14 (Xinhua) -- Japan's Nuclear Regulation Authority (NRA) said Monday that the process for restarting 10 reactors has stalled due to the plant's operators failing to provide necessary documents for safety inspections to proceed.

According to NRA representatives, six power plants that were shuttered in the wake of the earthquake-triggered tsunami that battered the Fukushima Daiichi plant in Japan's northeast in March 2011 leading to the worst nuclear crisis since Chernobyl, are facing delayed restarts due to the NRA's hold up in receiving relevant safety documents from the utilities.

Among the four utilities, operating the 10 reactors at six power plants are Hokkaido Electric Power Co. that operates the Tomari plant, Shikoku Electric Power Co. that is responsible for the Ikata plant, Kyushu Electric Power Co. that runs the Sendai plant and Tokyo Electric Power Co. (TEPCO) that is seeking to restart two of their idled reactors at the Kashiwazaki-Kariwa nuclear power plant in Niigata prefecture.

The NRA said its inspections at all of the facilities are at varying stages but delays would continue as long as the utilities continue to submit crucial safety documents and clarification of their content in an untimely manner.

Delays at the Tomari plant have been further prolonged due to the NRA requesting further information and analysis on the plant's subsurface and structural integrity in light of the fact that a sizable earthquake could be intensified due to subsurface and structural issues, according to an NRA spokesperson.

Inspections of the plant have subsequently been put on hold, with NRA representatives saying that their ongoing safety inspections could take a further six months.

The Secretariat of Japan's NRA Katsuhiko Ikeda has told embattled TEPCO chief Naomi Hirose that due to an increasing number of preventable toxic leaks at its Fukushima Daiichi facility, the restarting of its idled reactors at its Kashiwazaki- Kariwa nuclear power plant would be contingent on the NRA receiving an unequivocal safety report on the Fukushima leaks crisis and a clear roadmap for their solutions.

Separately, experts from the International Atomic Energy Agency (IAEA) on Monday began advising Japan on how best to deal with decontamination processes at TEPCO's crippled nuclear facility in Fukushima prefecture.

The delegation's week-long mission is being headed by Juan Carlos Lentijo, the director of the IAEA's Division of Nuclear Fuel Cycle and Waste Technology, and will conclude with the team making recommendations to the utility and the government on how best to deal with its mounting task of decontaminating hundreds of tons of water that is accumulating at the stricken plant on a daily basis.

The 16-member team of experts' visit marks the second time the IAEA has sent a delegation to Japan to advise on the ongoing nuclear crisis since October 2011.

The experts' visit to Fukushima to inspect decontamination sites was at the government's request and comes at a time when TEPCO has been in the headlines for a number of gaffes involving human error that have led to radioactive water leaking into the Pacific Ocean and workers being exposed to radioactive materials.